Curb boxes are employed widely to facilitate access to buried utility service valves and lines such as are customarily part of gas and water distribution systems. Generally, a curb box includes a housing at one end and a stem extending from the housing. The housing is configured so that it can overlie and cover a buried utility valve. The housing is buried during installation of the curb box and the housing protects and forms a space between the valve and the housing which is free of fill and permits access to the valve. The stem is generally an elongated tubular member fabricated of a single piece of tubing, which provides the vertical passage through which the valve, within the curb box, can be accessed. For example, an elongated key can be inserted down through the vertical passage to contact the valve or an extension therefrom within the housing or within the stem. The elongated tubular member is also partially or totally buried during installation of the curb box. Ultimately, following completion of construction and final grading of the property, only an opening at the upper end of the tubular member is exposed at ground surface. A cap may be installed on the upper end of the stem.
When installing a curb box, an open trench is dug in the ground in which the utility service distribution piping and associated valve are laid. The curb box housing, with the stem extending upwardly therefrom, is placed over the valve, and the trench is back filled, generally to the then prevailing “grade level” often referred to as the “pre-grade”. The housing is entirely buried by the back fill. A lower portion of the stem is buried to pre-grade level but an upper portion is customarily allowed to protrude above pre-grade level so as to serve as a marker for the location of the valve and to permit access from above ground to open and close the valve below ground. The upper portion of the stem remains exposed above grade level until completion of construction when final grading including addition of top soil and turf is completed thereby bringing the fill around the curb box up to final ground surface, what is called the “final grade”. At that point, either the final grade is adjusted so the curb box stem and cap are covered until only the upper surface of the curb box cap remains exposed or the length of the curb box stem is adjusted so the top of the cap on the stem is level with the final grade.
During construction prior to final grading, however, the upper portion of the curb box stem that protrudes above pre-grade level is susceptible to damage by any lateral application of force. In particular, after back filling and prior to final grading, the protruding, upper portion of the elongated tubular member is generally exposed to construction traffic including, but not limited to cars, pick-up and delivery trucks as well as heavy construction vehicles such as cement trucks, fork lifts, front end loaders, bob cats, blades, etc. When exposed to this type of traffic, the curb box may be impacted by lateral forces that damage the stem. This damage may bend the tubular member irreversibly, thereby pinching off the vertical passage and preventing access to the valve contained in the housing at the bottom of the curb box.